The carbonation of liquid beverages extends into antiquity. The ancient Egyptians produced a carbonated beverage similar to present day beer and the production of carbonated wines (sparkling wines) extends beyond historical records. Thus, it has been known for centuries that the carbonation of a beverage can significantly affect the taste and mouth feel of that beverage. A notable example of the significance of carbonation on taste and mouth feel has been experienced by all who have consumed a flat (decarbonated) beer or soft drinks. Consumers have for centuries made most significant distinctions between products which are uncarbonated and the same products which are carbonated. For example, the naturally occurring carbonated waters of France have long since been prized beverages, as opposed to natural uncarbonated waters, and consumers recognize that the carbonated version of the water taste considerably different from the uncarbonated version.
For over a century efforts have been made in the art to artifically carbonate beverages, as opposed to natural carbonation which occurs during beer making, wine making, and in naturally carbonated waters. Artifically carbonated beverages, such as carbonated water, have long since been a popular beverage both for consumption per se and for mixing with other beverages, such as producing an alcoholic mixed drink. In addition, a large industry exists in the World in regard to flavored carbonated water (the soft drink industry).
However, carbonated beverages have been restricted, primarily, to naturally carbonated alcoholic beverages such as beer and wine, or artifically carbonated water. This is because the carbonation generally lowers the pH of the carbonated beverage, and many beverages, aside from alcoholic beverages and water, contain systems which are unstable at the lower pHs produced during carbonation of the beverage.
In the latter regard, liquid dairy products, such as whole milk, are subject to such destabilization upon carbonation. Accordingly, a practical process for carbonating liquid dairy products, while avoiding destabilization, was never developed by the art. The destabilization of a liquid dairy product manifests itself in several manners, depending upon the degree of carbonation (and hence pH of the carbonated liquid dairy product). For example, whole milk can be lightly carbonated without any substantial destabilization. Indeed, whole milk which has not been otherwise processed contains a small amount of natural carbonation. However, that slight amount of natural carbonation is not sufficient to substantially affect the taste and mouth feel of the whole milk. There are, however, consumers who can detect a difference in taste between unprocessed whole milk and whole milk which has been processed, and hence, decarbonated.
An early attempt at carbonating whole milk is disclosed in U.S. Pat. No. 607,362. The intended purpose of that carbonation was to make the milk more durable (somewhat preserved) and more easily digestible. In addition to carbonation, formaline was added to the milk for preservation purposes. That patent points out that un-identified earlier attempts in the art at carbonating milk were totally unsuccessful in that the carbonated milk entirely lost the character of a liquid and had, in fact, more the consistency of whipped cream. This, of course, demonstrates a result of destabilization of the milk. To avoid that difficulty U.S. Pat. No. 607,362 teaches that the milk should first be de-aerated. To de-aerate, the patent teaches heating the milk to 70.degree. to 75.degree. C. while the milk is under a vacuum, after which the de-aerated milk is carbonated. However, while the patent does not teach specific amounts of carbonation, from the process described in that patent, it is clear that the milk was only lightly carbonated, and as the art has subsequently found such light carbonation neither substantially extends the preservation time of the milk nor substantially changes the taste and mouth feel thereof. Accordingly, that process never achieved any commercial success.
Another attempt at carbonating milk is described in U.S. Pat. No. 2,394,303. That patent recounts the knowledge in the art of carbonating milk, including pasteurized and homogenized milk, but points out that those efforts in the art encountered a substantial difficulty in that the carbonated milk so easily foamed that the carbonated milk could not be packaged in containers such that the packaged carbonated milk would substantially fill the container when the foamed carbonated milk defoamed. The foaming of the carbonated milk is another manifestation of the milk having been destabilized by the carbonation. Apparently, in the prior art recited in that process, the destabilization of the milk by the carbonation was to such an extent that it required the carbonated milk to rest for many hours in order for the foamed carbonated milk to defoam. In addition, the destabilized milk was so destabilized that when the package of the carbonated milk was opened a turbulent gushing forth and spurting out of the contents of the package took place and that, according to that patent, objects in the vicinity, as well as persons opening the flask, are frequently soiled.
That patent sought to over-come the difficulties encountered by destabilization of the milk during carbonation by pre-cooling pasteurized and homogenized milk to about 4.degree. C. and then storing that cooled milk for a time period of about 24 hours, after which the rested milk is further cooled to about 0.degree. C. and then carbonated. The carbonated milk is then carefully transferred to yet a second carbonator where the carbonated milk is allowed to defoam and additional carbonation then takes place.
While this is an extremely laborious, and commercially non-practical, process, the process still failled to prevent destabilization of the milk in that the patent recites that with storage of the milk, the milk becomes viscous and froths after opening the sealed container of the carbonated milk or when pouring the carbonated milk into a glass. Thus, that process and the product thereof never enjoyed commercial success and was, essentially, the last serious attempt at a commercial process for carbonating milk in a liquid form.
In this latter regard, if a liquid dairy product, such as milk, is frozen, it can be carbonated without destabilization by the carbon dioxide, but the freezing destabilizes the milk itself, and any carbonation of a frozen liquid dairy product must, for practical purposes, remain in that frozen condition and consumed in that frozen condition. An example of the foregoing is U.S. Pat. No. 3,503,757.
Thus, the art was never successful in carbonating liquid dairy products, due to the destabilization effects, when the carbonation is to an extent as to have an appreciable affect on the dairy products, either by way of a taste and mouth feel affect or a preservation affect. The art, therefor, turned to the production of a simulated carbonated milk, but this simulated carbonated milk is really a carbonated water beverage which has added thereto some milk components, e.g., dried milk solids, whey and the like, along with flavoring to provide a clouded milk-like flavored soft drink. These simulated carbonated milk products, however, have neither the nutritional value of milk nor a taste or mouth feel resembling milk, but a taste and mouth feel more resembling a carbonated water beverage.
As can be appreciated, it would be an advantage to the art to carbonate a liquid dairy product to the extent that the taste and mouth feel of that dairy product can be significantly altered. For example, for dietary reasons, some consumers are instructed by physicians or other health professionals to use skim milk in place of whole milk. However, many consumers find the taste of skim milk to be unacceptable, since skim milk has a distinctive dairy protein flavor, which is objectionable to many consumers. While whole milk, on the other hand, has a sufficient fat content that the milk protein taste of skim milk is over-ridden, many consumers find the fat taste and mouth feel of whole milk to be objectionable, in that the fat taste and mouth feel lingers in the oral cavity substantially after the milk is consumed. This lingering fat taste and mouth feel also considerably reduce the refreshing taste of whole milk, as opposed to the refreshing taste of, e.g., carbonated water.